Learning about successfully implemented sustainability policies abroad increases support for sustainable domestic policies

Anthropogenic climate change poses an existential threat to life on Earth, hastening the need to generate support for sustainability policies. Four preregistered studies (total N = 2524) tested whether informing United States citizens about the successful implementation of sustainability policies abroad increased support for similar domestic policies. Studies 1 and 2 found that learning about the successful implementation of sustainability policies (reducing automobile use, using wind energy) abroad increased (1) support for similar domestic policies, (2) intentions to modify behavior to facilitate the adoption of sustainability policies, and (3) behavioral support for sustainability policies. Study 3 found that learning about sustainability policies in both WEIRD (Western, Educated, Industrialized, Rich, Democratic) (France) and non-WEIRD (Colombia) countries increased support for similar domestic policies. Study 4 found that learning about sustainability policies abroad increased support for domestic policy proposals that would impact participants’ city of residence. Overall, these findings suggest that educating citizens about the implementation of sustainability policies abroad can bolster support for domestic policies that combat climate change.

First, in 2021, transportation accounted for the largest portion (29%) of U.S. greenhouse gas emissions, with 58% of transportation emissions coming from light-duty vehicles 19 (e.g., passenger cars, trucks).Moreover, road transportation accounts for the largest share of premature deaths linked to emissions, with 53,000 early fatalities annually attributed to the exhaust emitted by cars and trucks 20 .Despite its importance, citizens often find sustainable transportation costly because most U.S. cities prioritize automobile transit 10 .Thus, policies that promote sustainable transportation infrastructure development, such as more bike paths and sidewalks, are crucial for mitigating climate change and saving lives.
Second, the U.S. 's energy infrastructure is highly reliant on fossil fuels, which exacerbate climate change 21 .Though many citizens may wish to power their homes sustainably, it is often not feasible given the limited availability of energy alternatives in the United States.Expanding wind energy infrastructure would substantially reduce air pollution and could save the U.S. up to $500 billion from reduced pollutants and $280 billion in natural gas costs by 2050 22 .Thus, bolstering support for developing wind energy infrastructure in the U.S. is important.Given that extant transportation and energy infrastructure in the U.S. contribute significantly to climate change, we tested whether our intervention encourages support for sustainably restructuring these sectors.
Four preregistered studies (total N = 2524) tested whether informing United States citizens about successfully implemented sustainability policies in other countries increased support for similar domestic sustainability policies.Studies 1-4 are methodologically similar in that they all explore how learning about sustainability policies in another country affects attitudes and behaviors towards similar policies domestically.All studies contain slight deviations from one another to conceptually replicate and extend our core finding in different ways: Study 2 examines a different sustainability policy (wind energy instead of sustainable transportation) from the other studies and also differs by including a behavioral donation measure to assess support for the policy.Study 3 contains a different treatment condition from the other studies in which participants learn about sustainability policies in a non-WEIRD 23 (Western, Educated, Industrial, Rich, Democratic) reference country (Bogota, Columbia).Study 4 differs from the other studies by recruiting residents of Chicago, Illinois, to examine our findings in a context concerning a local sustainability policy that directly affects the study population.By using a broadly consistent methodology with important alterations across studies, these studies build on each other to suggest that educating citizens about the implementation of sustainability policies abroad can bolster support for similar domestic policies.
We preregistered all studies at AsPredicted.Org.All preregistrations, Supplementary materials (including demographic information, exclusion criteria, stimuli, items, and additional analyses), and data can be accessed at: https:// resea rchbox.org/ 2278 [passcode: THLPJX].The Institutional Review Board at a Midwestern university approved all experimental protocols, and the researchers carried out all methods per the guidelines and regulations the IRB put forth.

Study 1
Study 1 tested whether learning about the successful implementation of sustainable urban planning policies that prioritized biker and pedestrian transportation over automobile traffic in Paris, France, increased U.S. citizens' support for similar policies in the U.S. We predicted that participants who learned about the implementation of these policies abroad would be more likely to support similar policies in the U.S.

Participants
We recruited 600 Prolific respondents who were U.S. residents.We recruited enough participants to detect a small effect of our intervention (d = 0.25) with 80% power.We excluded seven participants for failing a manipulation check ("What was the topic of the article you read?"), leaving a final sample size of 593.Among participants in the final sample, 290 were Democrats, 322 were female, 420 were White/Caucasian, and the mean age of participants was thirty-seven.Although we did not target a nationally representative sample, in all studies we sought to recruit a diverse sample across political affiliation, gender, ethnicity, and age.In this study and all subsequent studies, we obtained informed consent from all participants at the outset of the study.

Procedure
We randomly assigned participants to one of two conditions: learning vs. control.In the learning condition, participants read an article about how Paris implemented urban planning policies that transformed automobile infrastructure to prioritize biker and pedestrian transportation.In the control condition, participants read an article describing contemporary urban planning in the United States, which emphasizes automobile transit.Throughout our studies, we used various control conditions that matched the content of treatment conditions without evoking ideas about the successful implementation of policies in other countries.The online supplement provides all experimental stimuli used, as well as exclusion criteria and demographic information for each study.

Measures
After reading the article, participants completed four measures that assessed support for domestic sustainable urban planning policies.

Attitude measure
We measured participants' attitudes towards proposed changes in domestic urban planning using a three-item measure, which asked participants, "How strongly do you support the following measures: (1) Re-purposing highways for pedestrians and cyclists?(2) Re-purposing on-street car parking for bicycle lanes?(3) Making biking safer and more accessible in American cities?" We measured all items on a seven-point Likert scale (1 = Not at all, 7 = Strongly support; α = .86). www.nature.com/scientificreports/

Behavioral intentions
We measured participants' willingness to engage in sustainable behaviors using a three-item measure that asked participants, "How willing would you be to… (1) Decrease your reliance on automobile transportation in the future?(3) Vote in favor of initiatives that promote the walkability and bikeability of cities and towns in your state?"We measured all items on a seven-point Likert scale (1 = Not at all, 7 = Extremely willing; α = .91).

Urban planning priorities
We measured the extent to which participants wanted the United States to prioritize urban planning initiatives that support biker and pedestrian versus automobile transportation using a single item, which asked, "Over the next 50 years, to what extent do you think that United States infrastructure plans should prioritize…" (1 = Biker, pedestrian, and public transportation, 7 = Automobile transportation).

Behavioral measure
We included a single-item behavioral measure that asked participants whether they would rather read an article about sustainable or automobile transit at the end of the study.

Results
Participants in the learning condition supported domestic sustainable urban planning policies more than participants in the control condition, t(591) = 6.12, p < .001,d = 0.50, expressed more willingness to adopt sustainable transportation behaviors, t(591) = 2.97, p = .003,d = 0.24, and were more likely to say that the U.S. should prioritize biker, pedestrian, and public transportation compared to participants in the control condition, t(591) = 4.11, p < .001,d = 0.34.Finally, participants in the learning condition were more likely to choose to read an article about sustainable urban planning policies in the United States (85%) than participants in the control condition (74%), χ 2 (1, 593) = 10.60,p < .001.We present the means and standard deviations for all items across studies in Table 1.The results for our key dependent measure-support for domestic sustainability policies-by condition across all studies is shown in Fig. 1.

Discussion
Overall, participants who learned about the successful implementation of sustainable urban planning policies abroad expressed more support for similar domestic policies, more willingness to adopt sustainable transportation habits, and more interest in learning about sustainable urban planning.

Study 2
Study 2 conceptually replicated Study 1 using a different policy domain in a different reference location in the learning condition.Specifically, Study 2 examined whether learning about the successful implementation of wind energy infrastructure in Denmark increased support for policies that promote wind energy infrastructure in the U.S.

Participants
We recruited 600 Prolific respondents who were U.S. residents.We recruited enough participants to detect a small effect of our intervention (d = 0.25) with 80% power.We excluded four participants for failing a manipulation check, leaving a final sample size of 596.Of these, 301 were Democrats, 307 were female, 409 were White/ Caucasian, and the mean age of participants was thirty-eight.We obtained informed consent from all participants at the outset of the study.

Procedure
We randomly assigned participants to one of two conditions: a learning condition or a control condition.In the learning condition, participants read an article describing wind energy infrastructure in Denmark.In the control condition, participants read an article about existing energy infrastructure in the United States.

Measures
After reading the article, participants completed three measures that assessed support for domestic sustainable energy policies.

Attitude measure
We measured participants' attitudes towards proposed changes in domestic energy infrastructure policies using a three-item measure (α = .92),which asked participants, "How strongly do you support the following measures: (1) Reducing reliance on fossil fuels in the U.S.? (2) Building more wind turbines to increase the amount of wind energy generated in the U.S.? (3) Prioritizing wind energy infrastructure over fossil fuel energy infrastructure in the U.S.?" Participants responded to all items on a seven-point Likert scale (1 = Not at all, 7 = Strongly support).

Behavioral intentions
We measured participants' willingness to engage in sustainable behaviors and behaviors that would promote sustainable structural changes to energy infrastructure in the United States using a five-item measure (α = .92),which asked participants, "How willing would you be to… (1) Sign a petition showing that you support the development of wind energy infrastructure in the United States?(2) Sign up for a program that uses wind energy to power your own home?(3) Vote in favor of policies that increase U.S. reliance on wind energy?(4) Financially invest in wind energy projects or companies?(5) Vote in favor of policies that decrease U.S. reliance on fossil fuels?"All items were measured on a seven-point Likert-scale (1 = Not at all, 7 = Extremely willing).

Behavioral measure
We collected a single-item behavioral measure.We measured how our manipulation affected participants' behaviors by giving participants a $1.00 bonus to allocate between an organization that promotes the development of wind energy infrastructure in the U.S. and an organization that promotes responsible fossil fuel use in the U.S.

Results
Compared to participants in the control condition, participants in the learning condition were more supportive of sustainable domestic energy infrastructure development, t(594) = 3.

Study 3
Studies 1 and 2 showed that participants support domestic sustainability policies more after learning about sustainability policies in a WEIRD (Western, Educated, Industrial, Rich, Democratic) reference country (i.e., France, Denmark) compared to the control condition.Study 3 tested whether learning about the successful implementation of sustainable urban planning policies in a non-WEIRD reference country (Bogota, Colombia) increased support for sustainable urban planning policies in the U.S. similarly to learning about urban planning in a WEIRD reference country (Paris, France; as in Study 1).

Participants
We recruited 899 Prolific respondents who were U.S. residents.We recruited enough participants to detect a small effect of our intervention (d = 0.25) with 80% power.We excluded fourteen participants for failing a manipulation check, leaving a final sample size of 885.Of these, 411 were Democrats, 453 were female, 673 were White/Caucasian, and the mean age of participants was forty-two.Participants gave informed consent at the outset of the study.

Procedure
We randomly assigned participants to one of three conditions: a WEIRD learning condition, a non-WEIRD learning condition, or a control condition.In the WEIRD learning condition, participants read the same article describing the successful implementation of sustainable urban planning policies in Paris, France that was used in Study 1.In the non-WEIRD learning condition, participants read an article describing the successful implementation of sustainable urban planning policies in Bogota, Colombia.In the control condition, participants read the same control article that was used in Study 1.
After reading the article, participants completed four measures that assessed support for domestic sustainable urban planning policies.These included the same three-item attitudinal measure (α = .86),three-item behavioroid measure (α = .91),and single-item priority measure from Study 1, and a single-item resource allocation task in which participants allocated a $1 bonus between an organization promoting biking in U.S. cities (People for Bikes) and an organization supporting safe and efficient automobile transit in America (Transportation for America).
Further, participants who learned about urban planning in Bogota were also more supportive of sustainable domestic urban planning policies than participants in the control condition, t(586) = 3.60, p < .001,d = 0.30, were more willing to adjust their behavior, t(586) = 2.64, p = .008,d = 0.22, and showed greater support for prioritizing www.nature.com/scientificreports/control condition who learned about innovation abroad.The pattern of results for other measures were in the same direction of our main effect between conditions but did not reach statistical significance.

Discussion
The current work introduced a novel intervention that increased support for sustainability policies in the U.S. Four preregistered studies found evidence that learning about the successful implementation of sustainability policies abroad increased attitudinal and behavioral support for domestic sustainability policies.Moreover, we found promising evidence in support of the potential generalizability of this effect.Specifically, we found that this effect persisted across policy domains (urban planning, wind energy), with WEIRD and non-WEIRD reference countries (France, Denmark, Colombia), and when individuals considered actual sustainability policies proposed in their own city.Our work adds to a growing body of literature that uses psychological interventions to combat the climate crisis 24,25 .We note that our intervention appears to work for both liberals and conservatives (see Supplementary Materials for analyses with political ideology).Thus, our intervention may be a promising avenue to increase support for sustainability policies among less climate-interested groups, such as U.S. conservatives.
Although we observed consistent effects on self-reported support for sustainability policies, our intervention clearly impacts some behaviors (e.g., desire to learn more about sustainability policies, allocating more resources to sustainability organizations) more than others.However, given that the effects were in the hypothesized direction for all measures across all studies, future studies with larger samples may reveal more consistent effects of our intervention on various behavioral measures.Future research can also better assess any disconnects between support for sustainable policies and behaviors.
Another direction for future research is to examine the effect in other populations.Although we suspect our intervention will affect non-U.S.samples similarly to U.S. samples, future research can test its generalizability more explicitly.For instance, feelings of nationalism may moderate the efficacy of our intervention, making it less effective in highly nationalistic countries where other countries' success is less relevant to the success of one's home country.Our intervention may also be particularly effective in countries that value multiculturalism and are highly open to alternative policy innovations that originate in places outside one's home country.
Finally, although we demonstrate an immediate shift in attitudes and intentions, future research can test the extent to which these effects persist over time.Existing work has shown that similar brief messaging interventions that encourage sustainable attitudes and behaviors have durable effects on energy consumption that can last weeks after implementation 26 , suggesting the possibility that an intervention like ours may endure as well, at least to an extent.
This intervention holds the potential to advance support for sustainability policies.Politicians and governments aiming to implement such policies stand to benefit by informing citizens about analogous successful initiatives in other countries, underscoring the tangible benefits accrued by those nations.This approach not only provides policymakers with a persuasive tool to garner public backing but also fosters a sense of feasibility and desirability among citizens.Moreover, learning about successful sustainability initiatives elsewhere has the potential to shape individual behavior.When citizens learn about the successful implementation of sustainability policies in other nations, there may be a behavioral shift at the grassroots level.Individuals, inspired by these success stories, may be more inclined to support similar domestic sustainability policies and adopt environmentally friendly practices in their daily lives.

Table 1 .
Means and standard deviations for items across all studies.*Lower scores indicate higher priority.
DiscussionOverall, Study 2 further demonstrated that learning about successfully implemented sustainability policies abroad increases support for similar domestic policies.Study 2 extended the findings of Study 1 by using another reference country (Denmark) in another domain critical to combatting climate change (energy infrastructure and consumption).